I'm using IIS 5.0 on Windows 2000 Professional for development, I'm not sure when this started happening but the APP mappings disappeared for some of the webs I have, including iishelp, the only one left is for .printer. The same happens for newly created webs. The result is that when I try to open an .ASP page I get a Save As dialog, instead of the page being executed.

I fixed this by adding the mapping for the ASP extension manually, but this wasn't required before, all the mappings, including those for .NET where automatically generated when I created the application (Web properties -> Application Settings), how can I restore this behaviour.

Additional information:

I recently installed the update for the .NET framework, and upgraded IE form 5.0 to 5.5